Heater unit



FIG. 1 is a top, front, and left side perspective view of a heater unit of our design;

FIG. 2 is a bottom, front, and right side perspective view thereof;

FIG. 3 is a top view thereof;

FIG. 4 is a bottom view thereof;

FIG. 5 is a right side view thereof;

FIG. 6 is a left side view thereof;

FIG. 7 is a rear view thereof; and,

FIG. 8 is a front view thereof. 

CLAIM The ornamental design for a heater unit, as shown and described. 